Recent technological advancements in treating type 1 diabetes have recently been described in The Lancet.
Type 1, or juvenile, diabetes is an autoimmune disease where the body mistakes its own cells – β-cells in the pancreas – for foreign cells and subsequently tries to get rid of them. There are numerous treatments for the management of type 1 diabetes, all of which revolve around regulating the amount of insulin in the blood, which in turn will control blood sugar levels. There is a fine balance between administering too much insulin which can cause hypoglycaemia and administering too little which results in hyperglycaemia. Hypoglycaemias or low blood sugar levels can lead to seizures and loss of consciousness. There are two main components to managing diabetes these include monitoring the amount of glucose in the blood and then administering the right amount of insulin.
Glucose Monitoring
Self-monitoring of Blood Glucose
Patients with type 1 diabetes can monitor their glucose levels with portable blood glucose meters. The meters have become smaller and more accurate over time and require 2–10 μL (1 microliter is one-thousandth of a millilitre) of blood and can process the samples in 5-15 seconds. This type of monitoring has to be performed numerous times a day to ensure correct insulin dosage. Some patients are asked to check their glucose up to 10 times a day. For example, the glucose levels should be monitored before and after meals, before physical activity, and before driving. Some monitors can share their data with smartphone apps, insulin pumps and data can be stored in the cloud to help keep track of fluctuations in glucose levels.
Continuous Monitoring of Blood Glucose
In the past couple of years, continuous blood glucose monitors have begun to emerge to help collect more complete data for each patient. These devices have been used to compliment the readouts provided by glucose meters. Continuous monitors have subcutaneous sensors that measure glucose in the interstitial fluid every 1-5 minutes. The glucose levels in the interstitial fluid are comparable to those in the bloodstream when glucose levels are stable. However, if there are rapid changes in glucose there is a lag of 7–8 min in the readout for type 1 diabetics. This may be problematic when ketoacidosis, hyper- and hypoglycaemic events occur. Three continuous monitors have received FDA approval to be used as replacements for glucose meters, they can be used to guide insulin dosage. They are the Dexcom G5 sensor (Dexcom, San Diego, CA, USA), the Abbott Freestyle Libre (Abbott Diabetes Care, Alameda, CA, USA) and the Senseonics Eversense (Senseonics, Germantown, MD, USA).
Insulin Delivery
Once the blood glucose levels have been determined the correct amount of insulin can be administered to maintain glycaemic control. Insulin can be delivered in one of two ways either by direct injection or insulin pump therapy.
Direct injection
Originally, insulin was drawn out of a vial and injected into the patient, and while some patients continue with this mode of administration there have been advancements in technology to help with this process. Many patients now use insulin pens that combine the vial and syringe into a single device. The pens have a disposable and refillable cartridge system that contains insulin. There are even smartpens that will track insulin dose and time that will send this information to smartphones or the cloud to help monitor usage. These injections are generally given once or twice daily and before meals.
Insulin-pump therapy
The alternative to direct injection is through the use of insulin pumps, these are devices that administer a continuous subcutaneous insulin injection. The device consists of a small pump connected to a cannula (needle) via some tubing. Some devices have the needle directly connected to the reservoir of insulin and it is remotely controlled so there is no need for tubing. The advantage of using insulin pumps is that they are programmable and different infusion rates can be used during the day, particularly before meals. They are well suited to children and those that have needle phobias as the needle is changed every three days. Insulin pumps are on average 1.4 times more expensive than daily injections and problems with infusion sets have been observed.
Moving toward the Bionic Pancreas
More and more systems are moving toward the idea of automated insulin delivery or the development of a bionic pancreas. The core elements of one of these systems requires an insulin infusion pump, continuous glucose monitoring and an algorithm that determines when to administer insulin. The first automated insulin delivery system Medtronic 670G (Medtronic Diabetes, Northridge, CA, USA) was available in the USA in 2017 and 2018 in Europe. This system is not fully automated however, the user has to input information for planned meals and carbohydrate intake to activate insulin injections for meals. Medtronic 670G system is the only partly automated system that has regulatory approval however Diabeloop (Grenoble, France) is expected to become available in Europe this year. Scientists are still working on developing fully automated systems.
The technology for managing type 1 diabetes has progressed considerably over the past decade. There is a myriad of options available to help managed and maintain blood glucose levels. However, there is a lot of research that still needs to be done to optimize these technologies, allowing for easy and efficient regulation of insulin.
Written by Tarryn Bourhill Msc, PhD Candidate.
References:
- Association, A. D. 7. Diabetes technology: standards of medical care in diabetes—2019. Diabetes Care 42, S71-S80 (2019).
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Daneman, D. Type 1 diabetes. The Lancet 367, 847-858 (2006).
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Martin, C. T., Criego, A. B., Carlson, A. L. & Bergenstal, R. M. Advanced Technology in the Management of Diabetes: Which Comes First—Continuous Glucose Monitor or Insulin Pump? Current Diabetes Reports 19, 50 (2019).
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Ilonen, J., Lempainen, J. & Veijola, R. The heterogeneous pathogenesis of type 1 diabetes mellitus. Nature Reviews Endocrinology, 1-16 (2019).
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Kowalski, A. Pathway to artificial pancreas systems revisited: moving downstream. Diabetes care 38, 1036-1043 (2015).
Image by Steve Buissinne from Pixabay
